//  命名空间
//  可以当作模块导出
//  可以用来防止重名的错误
export namespace A{
    // 里面的类也需要导出
   export class Students{
        public name:string | undefined
        public password:string | undefined
        public id:string | undefined
        constructor(name:string|undefined,password:string|undefined,id:string|undefined){
            this.name = name
            this.password = password
            this.id = id
        }
    }
}
